3,127 research outputs found
Susy QCD and High Energy Cosmic Rays 1. Fragmentation functions of Susy QCD
The supersymmetric evolution of the fragmentation functions (or timelike
evolution) within N=1 is discussed and predictions for the fragmentation
functions of the theory (into final protons) are given. We use a backward
running of the supersymmetric DGLAP equations, using a method developed in
previous works. We start from the usual QCD parameterizations at low energy and
run the DGLAP back, up to an intermediate scale -assumed to be supersymmetric-
where we switch-on supersymmetry. From there on we assume the applicability of
an N=1 supersymmetric evolution (ESAP). We elaborate on possible application of
these results to High Energy Cosmic Rays near the GZK cutoff.Comment: 36 pages, 12 fig
Interleukin 31 mediates MAP kinase and STAT1/3 activation in intestinal epithelial cells and its expression is upregulated in inflammatory bowel disease
Background/aim: Interleukin 31 (IL31), primarily expressed in activated lymphocytes, signals through a heterodimeric receptor complex consisting of the IL31 receptor alpha (IL31R\textgreeka) and the oncostatin M receptor (OSMR). The aim of this study was to analyse IL31 receptor expression, signal transduction, and specific biological functions of this cytokine system in intestinal inflammation.Methods: Expression studies were performed by RT-PCR, quantitative PCR, western blotting, and immunohistochemistry. Signal transduction was analysed by western blotting. Cell proliferation was measured by MTS assays, cell migration by restitution assays.Results: Colorectal cancer derived intestinal epithelial cell (IEC) lines express both IL31 receptor subunits, while their expression in unstimulated primary murine IEC was low. LPS and the proinflammatory cytokines TNF-\textgreeka, IL1\textgreekb, IFN-\textgreekg, and sodium butyrate stimulation increased IL31, IL31R\textgreeka, and OSMR mRNA expression, while IL31 itself enhanced IL8 expression in IEC. IL31 mediates ERK-1/2, Akt, STAT1, and STAT3 activation in IEC resulting in enhanced IEC migration. However, at low cell density, IL31 had significant antiproliferative capacities (p<0.005). IL31 mRNA expression was not increased in the TNF\textgreekDARE mouse model of ileitis but in inflamed colonic lesions compared to non-inflamed tissue in patients with Crohn's disease (CD; average 2.4-fold increase) and in patients with ulcerative colitis (UC; average 2.6-fold increase) and correlated with the IL-8 expression in these lesions (r = 0.564 for CD; r = 0.650 for UC; total number of biopsies analysed: n = 88).Conclusion: IEC express the functional IL31 receptor complex. IL31 modulates cell proliferation and migration suggesting a role in the regulation of intestinal barrier function particularly in intestinal inflammation
Direct computation of elliptic singularities across anisotropic, multi-material edges
We characterise the singularities of elliptic div-grad operators at points or edges where several materials meet on a Dirichlet or Neumann part of the boundary of a two- or three-dimensional domain. Special emphasis is put on anisotropic coefficient matrices. The singularities can be computed as roots of a characteristic transcendental equation. We establish uniform bounds for the singular values for several classes of three- and four-material edges. These bounds can be used to prove optimal regularity results for elliptic div-grad operators on three-dimensional, heterogeneous, polyhedral domains with mixed boundary conditions. We demonstrate this for the benchmark L--shape problem
Elliptic model problems including mixed boundary conditions and material heterogeneities
We present model problems in three dimensions, where the operator
maps the Sobolev space
isomorphically onto
for a . The emphasis is here on the
case where different boundary conditions meet material
heterogeneities
Lie Group Structures on Symmetry Groups of Principal Bundles
In this paper we describe how one can obtain Lie group structures on the
group of (vertical) bundle automorphisms for a locally convex principal bundle
P over the compact manifold M. This is done by first considering Lie group
structures on the group of vertical bundle automorphisms Gau(P). Then the full
automorphism group Aut(P) is considered as an extension of the open subgroup
Diff(M)_P of diffeomorphisms of M preserving the equivalence class of P under
pull-backs, by the gauge group Gau(P). We derive explicit conditions for the
extensions of these Lie group structures, show the smoothness of some natural
actions and relate our results to affine Kac--Moody algebras and groups
Inducing Transport in a Dissipation-Free Lattice with Super Bloch Oscillations
Particles in a perfect lattice potential perform Bloch oscillations when
subject to a constant force, leading to localization and preventing
conductivity. For a weakly-interacting Bose-Einstein condensate (BEC) of Cs
atoms, we observe giant center-of-mass oscillations in position space with a
displacement across hundreds of lattice sites when we add a periodic modulation
to the force near the Bloch frequency. We study the dependence of these "super"
Bloch oscillations on lattice depth, modulation amplitude, and modulation
frequency and show that they provide a means to induce linear transport in a
dissipation-free lattice. Surprisingly, we find that, for an interacting
quantum system, super Bloch oscillations strongly suppress the appearance of
dynamical instabilities and, for our parameters, increase the phase-coherence
time by more than a factor of hundred.Comment: 4 pages, 5 figure
Marching at the front and dragging behind: differential αVβ3-integrin turnover regulates focal adhesion behavior
Integrins are cell–substrate adhesion molecules that provide the essential link between the actin cytoskeleton and the extracellular matrix during cell migration. We have analyzed αVβ3-integrin dynamics in migrating cells using a green fluorescent protein–tagged β3-integrin chain. At the cell front, adhesion sites containing αVβ3-integrin remain stationary, whereas at the rear of the cell they slide inward. The integrin fluorescence intensity within these different focal adhesions, and hence the relative integrin density, is directly related to their mobility. Integrin density is as much as threefold higher in sliding compared with stationary focal adhesions. High intracellular tension under the control of RhoA induced the formation of high-density contacts. Low-density adhesion sites were induced by Rac1 and low intracellular tension. Photobleaching experiments demonstrated a slow turnover of β3-integrins in low-density contacts, which may account for their stationary nature. In contrast, the fast β3-integrin turnover observed in high-density contacts suggests that their apparent sliding may be caused by a polarized renewal of focal contacts. Therefore, differential acto-myosin–dependent integrin turnover and focal adhesion densities may explain the mechanical and behavioral differences between cell adhesion sites formed at the front, and those that move in the retracting rear of migrating cells
Preparation and spectroscopy of a metastable Mott insulator state with attractive interactions
We prepare and study a metastable attractive Mott insulator state formed with
bosonic atoms in a three-dimensional optical lattice. Starting from a Mott
insulator with Cs atoms at weak repulsive interactions, we use a magnetic
Feshbach resonance to tune the interactions to large attractive values and
produce a metastable state pinned by attractive interactions with a lifetime on
the order of 10 seconds. We probe the (de-)excitation spectrum via lattice
modulation spectroscopy, measuring the interaction dependence of two- and
three-body bound state energies. As a result of increased on-site three-body
loss we observe resonance broadening and suppression of tunneling processes
that produce three-body occupation.Comment: 7 pages, 6 figure
A cluster randomised school-based lifestyle intervention programme for the prevention of childhood obesity and related early cardiovascular disease (JuvenTUM 3)
<p>Abstract</p> <p>Background</p> <p>Childhood obesity is not only associated with adult obesity but also with increased risk of adult onset of type 2 diabetes and subsequent coronary heart disease. The potential effects of school-based health intervention programmes on cardiovascular risk and surrogate markers are unclear, as only few studies have attempted to investigate a complete risk profile including a detailed laboratory analysis or micro- and macrovascular function. In this study a comprehensive school-based randomized intervention programme will be investigated in 10-14-year old children addressing the influence of lifestyle intervention on inactivity, cardiometabolic risk factors and early signs of vascular disease.</p> <p>Methods/Design</p> <p>15 secondary schools in Southern Germany are randomly assigned to intervention or control schools. Children in the fifth grade (10-11 years) will be observed over four years. The study combines a school-based with a home-based approach, aiming at children, teachers and parents. The main components are weekly lifestyle-lessons for children, taught by regular classroom teachers to increase physical activity in- and outside of school, to improve eating patterns at school and at home, to reduce media consumption and to amplify well-being. In 4-6 annual meetings, teachers receive information about health-related topics with worksheets for children and supporting equipment, accounting for school-specific needs and strategies. Parents' trainings are provided on a regular basis.</p> <p>All examinations are performed at the beginning and at the end of every school year. Anthropometry includes measurements of BMI, waist and upper arm circumferences, skinfold thickness as well as peripheral blood pressure. Blood sampling includes lipid parameters, insulin, glucose, hsCRP, adiponectin, and IL-6 as well as testosteron and estrogen to determine maturation status. Vascular function is non-invasively assessed by measuring arterial stiffness in large arteries using a sphygmograph and by analysing arteriolar and venular diameters in the retinal microcirculation using a non-mydriatric vessel analyser. A questionnaire is filled out to determine daily physical activity, motivational factors, dietary habits, quality of life (KINDL-R) and socio-economic data. Physical fitness is assessed by a six-item test battery.</p> <p>Discussion</p> <p>Our study aims to provide a feasible long-term intervention strategy to re-establish childhood health and to prevent obesity-related cardiovascular dysfunction in children.</p> <p>Trial Registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT00988754">NCT00988754</a></p
Confinement-Induced Resonances in Low-Dimensional Quantum Systems
We report on the observation of confinement-induced resonances in strongly
interacting quantum-gas systems with tunable interactions for one- and
two-dimensional geometry. Atom-atom scattering is substantially modified when
the s-wave scattering length approaches the length scale associated with the
tight transversal confinement, leading to characteristic loss and heating
signatures. Upon introducing an anisotropy for the transversal confinement we
observe a splitting of the confinement-induced resonance. With increasing
anisotropy additional resonances appear. In the limit of a two-dimensional
system we find that one resonance persists.Comment: 4 pages, 4 figure
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